Hydraulic Oil Well Pumping System, and Method for Delivering Gas From a Well

ABSTRACT

A hydraulic oil well pumping system is provided. The system uses a pump to exert hydraulic pressure against a reciprocating lift piston over a wellbore. The lift piston is operatively connected to a rod string and downhole pump for pumping oil from a wellbore. Thus, oil is pumped from the wellbore as the rod string and downhole pump move between upper and lower rod positions. In addition, the system includes at least one compressor cylinder having a compressor piston that reciprocates with the lift piston in order to compress produced gas at the surface. A method for compressing gas while pumping oil from a wellbore using such a system is also provided herein.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Ser. No. 61/766,664, filedFeb. 19, 2013. That application is entitled “Hydraulic Oil Well PumpingSystem, and Method for Delivering Gas From a Well,” and is incorporatedherein in its entirety by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

This section is intended to introduce various aspects of the art, whichmay be associated with exemplary embodiments of the present disclosure.This discussion is believed to assist in providing a framework tofacilitate a better understanding of particular aspects of the presentdisclosure. Accordingly, it should be understood that this sectionshould be read in this light, and not necessarily as admissions of priorart.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to the field of hydrocarbon recoveryoperations. More specifically, the present invention relates tohydraulically actuated pumping units for the production of hydrocarbonfluids, and to the compression of produced gas for pressured deliveryinto a gas line.

2. Technology in the Field of the Invention

In the drilling of oil and gas wells, a wellbore is formed using a drillbit that is urged downwardly at a lower end of a drill string. Afterdrilling to a predetermined depth, the drill string and bit are removedand the wellbore is lined with a string of casing. An annular area isthus formed between the string of casing and the surrounding formations.

A cementing operation is typically conducted in order to fill or“squeeze” the annular area with columns of cement. The combination ofcement and casing strengthens the wellbore and facilitates the zonalisolation of the formations behind the casing.

It is common to place several strings of casing having progressivelysmaller outer diameters into the wellbore. A first string may bereferred to as surface casing. The surface casing serves to isolate andprotect the shallower, fresh water-bearing aquifers from contaminationby any other wellbore fluids. Accordingly, this casing string is almostalways cemented entirely back to the surface.

The process of drilling and then cementing progressively smaller stringsof casing is repeated several times until the well has reached totaldepth. In some instances, the final string of casing is a liner, thatis, a string of casing that is not tied back to the surface. The finalstring of casing, referred to as a production casing, is also typicallycemented into place.

As part of the completion process, the production casing is perforatedat a desired level. This means that lateral holes are shot through thecasing and the cement column surrounding the casing. The perforationsallow hydrocarbon fluids to flow into the wellbore. Thereafter, theformation is optionally acidized and/or fractured.

To prepare the wellbore for the production of hydrocarbon fluids, astring of tubing is run into the casing. A packer is optionally set at alower end of the tubing to seal an annular area formed between thetubing and the surrounding strings of casing. The tubing then becomes astring of production pipe through which hydrocarbon fluids may belifted. In some instances, produced gas is permitted to travel up thewellbore through the annular area.

In order to carry the hydrocarbon fluids to the surface, a pump may beplaced at a lower end of the production tubing. This is known as“artificial lift.” In some cases, the pump may be an electricalsubmersible pump, or ESP. ESP's utilize a hermetically sealed motor thatdrives a multi-stage pump. More conventionally, oil wells undergoingartificial lift use a downhole reciprocating plunger-type of pump. Thepump has one or more valves that capture fluid on a down stroke, andthen lift the fluid on the upstroke. This is known as “positivedisplacement.” In some designs such as that disclosed in U.S. Pat. No.7,445,435, the pump is able to both capture fluid and lift fluid on eachof the down stroke and the upstroke.

Conventional positive displacement pumps define a barrel that isreciprocated at the end of a “rod string.” The rod string comprises aseries of long, thin joints of pipe that are threadedly connectedthrough couplings. The rod string is attached to a pumping unit at thesurface. The pumping unit causes the rod string to move up and downwithin the production tubing to incrementally lift production fluidsfrom subsurface intervals to the surface.

Most pumping units on land are so-called rocking beam drive units.Rocking beam units typically employ electric motors or internalcombustion engines having a rotating drive shaft. The shaft turns acrank arm, or possibly a pair of crank arms. The crank arms, in turn,have heavy, counter-weighted flywheels. The flywheels rotate along withthe crank arms. Rocking beam units also have a walking beam. The walkingbeam pivots over a fulcrum. One end of the walking beam is mechanicallyconnected to the crank arms. As the crank arms and flywheels rotate,they cause the walking beam to reciprocate up and down over the fulcrum.

The opposite end of the walking beam is a so-called horse head. Thehorse head is positioned over the well head at the surface. As thewalking beam is reciprocated, the horse head cycles up and down over thewellbore. This, in turn, translates the rod and attached pump up anddown within the wellbore. A drawing and further description of a walkingbeam unit are provided in U.S. Pat. No. 7,500,390, which is incorporatedherein in its entirety by reference.

Another type of pumping unit is a hydraulic actuator system. Thesesystems employ an elongated cylinder that is positioned over a wellbore.The cylinder is axially aligned with the vertical wellbore and houses areciprocating piston. The cylinder cyclically receives fluid pressurethrough an external oil line. As fluid is injected through the oil lineand into the cylinder under pressure, the piston is caused to movelinearly within the cylinder. This, in turn, raises the connected rodstring, causing the pump to undergo an upstroke. When fluid pressure isreleased from the cylinder, the rod string is lowered due togravitational forces, causing the connected downhole pump to undergo adownstroke.

Surface hydraulic actuator systems have been used successfully for manyyears. Such systems offer a beneficially long stroke length for thedownhole plunger pump. Such systems are also ideal for urbanenvironments where a small footprint is demanded. Further, such systemsoffer the ability to operate more than one well from a single surfaceinstallation.

It is uniquely observed by the inventor herein that energy generated bythe gravitational forces exerted on the piston of a hydraulic pumpingsystem could be used as a source of “free” work. At the same time, aneed exists to compress gas being incidentally produced from the well onthe back side of the production tubing. Therefore, it is proposed hereinto employ gravitational forces available from the falling piston tocompress gas as it is delivered into a gas line.

BRIEF SUMMARY OF THE INVENTION

An oil well pumping system is first provided herein. The pumping systemcyclically directs a hydraulic fluid such as a clean oil into a liftcylinder. As the oil is pumped into the cylinder, the piston causes arod string and connected downhole pump to move up within a wellbore.This is an upstroke. Then, as the hydraulic fluid is released from thelift cylinder, the rod string and connected downhole pump drop withinthe wellbore due to gravitational forces. This is a downstroke.

Reciprocation of the lift piston and connected rod string and downholepump causes reservoir fluids to be produced from a wellbore and up tothe surface through positive displacement. Beneficially, the system alsouses the energy generated by gravitational forces as the piston and rodstring move in the downstroke to compress produced gas at the surface.This, in turn, moves gas downstream for treating, for sale, or for useas a combustible fuel.

In one aspect, the oil well pumping system first includes an elongatedhydraulic lift cylinder. The lift cylinder is positioned over thewellbore. The cylinder is preferably disposed vertically over anassociated wellhead.

The oil well pumping system also includes a lift piston and a liftcylinder rod. The lift piston and the lift cylinder rod reside withinthe lift cylinder and move together between upper and lower rodpositions. The lift cylinder rod defines an elongated rod while thepiston provides an annular seal between the lift cylinder rod and thesurrounding lift cylinder. Hydraulic pressure cyclically acts againstthe lift piston to create an upstroke and a down stroke for the liftcylinder rod.

The oil well pumping system further has a rod string. The rod string isoperatively connected to the lift piston. This means that when thepiston reciprocates, the rod string reciprocates with it. The rod stringextends downwardly from a polish rod at the wellhead and into a stringof production tubing in the wellbore. The rod string has a downhole pumpconnected to it for lifting fluids to the surface in response toreciprocation of the rod string.

In one aspect, the lift piston is operatively connected to the rodstring by means of a harness system. The harness system is connected toa lower end of the lift cylinder rod below the lift cylinder. Theharness system is also connected to an upper end of the polish rod. Theharness system has a block for receiving an upper end of the polish rod,and a clamp for securing the polish rod over the block.

The oil well pumping system also has at least one compressor cylinder.The compressor cylinder defines a barrel that houses a compressorpiston. Thus, the oil well pumping system also includes a compressorpiston in each compressor cylinder. The compressor pistons areconfigured to reciprocate within the respective compressor cylinders inresponse to movement of the harness system.

The oil well pumping system may also include a hydraulic pump. The pumpis powered by a prime mover. The prime mover may be an electric motor,an internal combustion engine, or other driver.

The oil well pumping system may further include a directional controlvalve. The directional control valve shifts between upstroke anddownstroke flow positions. When the valve is in its upstroke position,it directs hydraulic fluid such as oil from the pump and into theannular area formed below the piston between the lift cylinder rod andthe surrounding lift cylinder. When the directional control valve is inits downstroke (or neutral) position, it receives reverse flow from theannular area and allows the gravity-induced fall of the lift piston andconnected rod string.

The oil well pumping system also has an oil line. The oil line connectsthe pump and the hydraulic lift cylinder. The control valve ispositioned in the oil line so that it can control flow between the pumpand the cylinder in response to electrical signals. The signals are sentby an electrical control system that shifts the directional controlvalve between its upstroke and downstroke flow positions.

A fluid reservoir is also provided. The fluid reservoir containshydraulic fluid to be supplied to the pump.

The oil well pumping system may also comprises a reservoir line. Thereservoir line transmits hydraulic fluid from the cylinder back to thereservoir.

The compressor cylinders are in fluid communication with a gas line at awell site. The gas line extends from the wellhead and carriesnon-condensable fluids that are produced from the wellbore. Thenon-condensable fluids, such as methane gas, travel from the subsurfacereservoir and up the wellbore behind the string of production tubing.The non-condensable fluids then exit the wellbore through the gas lineat the wellhead. Check valves are provided so that gas flows through thecheck valves and into the compressor cylinders on the upstrokes, butthen flows down the gas line as pressure in the pipe is increased on thedown strokes.

A method of compressing produced gas at a well site is also providedherein. In the method, the well site has a wellbore that extends into anearth surface. The well site utilizes a pumping system that cyclicallydirects a hydraulic fluid such as a clean oil into a lift cylinder. Asthe oil is pumped into the lift cylinder, pressure acts against apiston, causing a rod string and connected downhole pump to move upwithin the wellbore as an upstroke. Then, as the hydraulic fluid isreleased from the lift cylinder, the rod string and connected downholepump drop within the wellbore as a down stroke.

Reciprocation of the lift piston and operatively connected rod stringand downhole pump causes reservoir fluids to be produced from a wellboreand up to the surface through positive displacement. Beneficially, thesystem also uses the energy generated by gravitational forces as thepiston and rod string move in the downstroke to compress produced gas atthe surface.

In one aspect, the method first comprises providing an elongatedhydraulic lift cylinder. The lift cylinder is positioned over thewellbore. The lift cylinder includes a lift piston that is movablebetween upper and lower rod positions. The lift piston creates anannular seal below the piston between a lift cylinder rod and thesurrounding lift cylinder. Hydraulic pressure acts against the liftpiston to cause the lift piston and connected lift cylinder rod to move.

The method also includes operatively connecting the lift piston to a rodstring. This may be done through a harness system and a polish rodbetween the lift piston and the rod string. When the lift pistonreciprocates, the polish rod and connected rod string reciprocate withit. Preferably, the rod string moves within a string of productiontubing that extends down to the depth of a subsurface reservoir. The rodstring has a downhole pump connected to it for lifting fluids to thesurface in response to reciprocation of the rod string.

The method also includes providing a hydraulic pump. Preferably, thepump is a variable displacement piston pump, although a fixeddisplacement pump may be used. The pump is powered by a prime mover. Theprime mover may be an electric motor, an internal combustion engine, orother driver.

The method also has the step of connecting the pump and the hydrauliccylinder with an oil line. The oil line transmits hydraulic fluid fromthe pump to the cylinder.

The method may also have the step of providing a fluid reservoir. Thereservoir contains hydraulic fluid to be supplied to the pump. Areservoir line transmits hydraulic fluid from the cylinder back to thereservoir.

The method further includes providing at least one compressor cylinder.Each compressor cylinder has a compressor piston that is movable betweenupper and lower rod positions in response to movement of the liftpiston. Thus, the compressor pistons are operatively connected to thelift piston.

In addition, the method includes placing the at least one compressorcylinder in fluid communication with a gas line. The gas line resides atthe surface and is used to transport non-condensable hydrocarbon fluidssuch as methane and ethane. Additional components may include hydrogensulfide, carbon dioxide, propane, and argon.

Further, the method has the step of producing non-condensablehydrocarbon fluids from the wellbore and into the gas line. Productionis preferably done by allowing gases to migrate from a subsurfacereservoir and up the wellbore behind the string of production tubing.The gases are directed into the gas line at the wellhead.

The method additionally provides for reciprocating the compressor pistonin order to increase pressure in the gas line. When the compressorpiston moves on its upstroke, it draws gas in through a check valve atthe wellhead. Then, when the compressor moves down on its downstroke, itmoves the produced gas along the gas line downstream.

Also, the method includes reciprocating the lift piston and mechanicallyconnected rod string within the wellbore. This step is the naturalresult of operation of the hydraulic pumping system having gascompression over time in order to pump oil from the wellbore.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the present inventions can be betterunderstood, certain illustrations, charts and/or flow charts areappended hereto. It is to be noted, however, that the drawingsillustrate only selected embodiments of the inventions and are thereforenot to be considered limiting of scope, for the inventions may admit toother equally effective embodiments and applications.

FIG. 1 is a side view of a hydraulic oil well pumping system of thepresent invention, in one embodiment. The hydraulic oil well pumpingsystem is used for producing hydrocarbon fluids from a subsurfaceformation to the surface at a well site as well as for compressingproduced gas. Portions of the system are shown schematically.

FIG. 2 is an enlarged side view of a portion of the hydraulic oil wellpumping system of FIG. 1. Here, the lift cylinder, the polish rod, andtwo compressor cylinders are more clearly seen.

FIG. 3 is a side cross-sectional view of a one of the compressorcylinders of FIG. 2, in one embodiment. A compressor piston is shown inmid-stroke.

FIG. 4A is schematic view of a hydraulic pumping system of the presentinvention, in one arrangement. Here, a lift cylinder piston and anoperatively connected compressor cylinder piston are on their downstrokes. Produced gas is being moved to a downstream facility along agas line.

FIG. 4B is schematic view of the hydraulic pumping system of FIG. 4A.Here, the lift cylinder piston and operatively connected compressorcylinder piston are on their up strokes. Produced gas is being drawninto the compressor cylinder while oil is being brought to the surface.

FIG. 4C is an enlarged, cross-sectional view of the hydraulic cylinder,hydraulic cylinder rod, and lift piston as may be used in the hydraulicrod pumping system of FIG. 1, in one embodiment. Here, a position sensoris used along the rod.

FIGS. 5A and 5B together present a flow chart showing steps that may beperformed for a method of compressing produced gas at an oil well site,in one embodiment.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS Definitions

For purposes of the present application, it will be understood that theterm “hydrocarbon” refers to an organic compound that includesprimarily, if not exclusively, the elements hydrogen and carbon.Hydrocarbons may also include other elements, such as, but not limitedto, halogens, metallic elements, nitrogen, oxygen, and/or sulfur.

As used herein, the term “hydrocarbon fluids” refers to a hydrocarbon ormixtures of hydrocarbons that are gases or liquids. For example,hydrocarbon fluids may include a hydrocarbon or mixtures of hydrocarbonsthat are gases or liquids at formation conditions, at processingconditions or at ambient conditions (15° C. to 20° C. and 1 atmpressure). Hydrocarbon fluids may include, for example, oil, naturalgas, coalbed methane, shale oil, pyrolysis oil, pyrolysis gas, apyrolysis product of coal, and other hydrocarbons that are in a gaseousor liquid state.

As used herein, the terms “produced fluids,” “reservoir fluids” and“production fluids” refer to liquids and/or gases removed from asubsurface formation, including, for example, an organic-rich rockformation. Produced fluids may include both hydrocarbon fluids andnon-hydrocarbon fluids. Production fluids may include, but are notlimited to, oil, natural gas, pyrolyzed shale oil, synthesis gas, apyrolysis product of coal, carbon dioxide, hydrogen sulfide and water(including steam).

As used herein, the term “fluid” refers to gases, liquids, andcombinations of gases and liquids, as well as to combinations of gasesand solids, combinations of liquids and solids, and combinations ofgases, liquids, and solids.

As used herein, the term “wellbore fluids” means water, mud, hydrocarbonfluids, formation fluids, or any other fluids that may be within astring of drill pipe during a drilling operation.

As used herein, the term “gas” refers to a fluid that is in its vaporphase at surface conditions.

As used herein, the term “subsurface” refers to geologic strataoccurring below the earth's surface.

As used herein, the term “formation” refers to any definable subsurfaceregion regardless of size. The formation may contain one or morehydrocarbon-containing layers, one or more non-hydrocarbon containinglayers, an overburden, and/or an underburden of any geologic formation.A formation can refer to a single set of related geologic strata of aspecific rock type, or to a set of geologic strata of different rocktypes that contribute to or are encountered in, for example, withoutlimitation, (i) the creation, generation and/or entrapment ofhydrocarbons or minerals, and (ii) the execution of processes used toextract hydrocarbons or minerals from the subsurface.

As used herein, the term “wellbore” refers to a hole in the subsurfacemade by drilling or insertion of a conduit into the subsurface. Awellbore may have a substantially circular cross section, or othercross-sectional shapes. The term “well,” when referring to an opening inthe formation, may be used interchangeably with the term “wellbore.” Theterm “bore” refers to the diametric opening formed in the subsurface bythe drilling process. (Note that this is in contrast to the term“cylinder bore” which may be used herein, and which refers to ahydraulic cylinder over a wellbore.)

DESCRIPTION OF SELECTED SPECIFIC EMBODIMENTS

FIG. 1 is a side view of a hydraulic oil well pumping system 100 of thepresent invention, in one embodiment. The hydraulic oil well pumpingsystem 100 is used for producing hydrocarbon fluids from a subsurfaceformation 110 to the surface 101 at a well site. In addition, thehydraulic oil well pumping system 100 is used for compressing producedgas at the surface 101.

In FIG. 1, it is first seen that the system 100 includes an elongatedlift cylinder 150. The lift cylinder 150 houses a lift cylinder rod 155.The lift cylinder rod 155 reciprocates up and down within the liftcylinder 150 in response to hydraulic pressure applied within the liftcylinder 150. Reciprocation creates an upstroke and a down stroke.

The lift cylinder rod 155 is mechanically connected to a harness system140. The harness system 140 reciprocates with the lift cylinder rod 155.As will be discussed more fully below, reciprocation of the harnesssystem 140 causes a polish rod 160 and connected rod string 130 toreciprocate within a wellbore 115. In addition, reciprocation of theharness system 140 causes a pair of compression cylinder rods toreciprocate at the surface 101.

At an upper end of the lift cylinder rod 155 is a piston 165. The piston165 seals an annular area 167 formed between the lift cylinder rod 160and the surrounding lift cylinder 150. The piston 165 prevents hydraulicoil from migrating into a chamber 169 above the piston 165. The annulararea 167 is filled with a working fluid, which is preferably a cleanhydraulic oil.

The piston 165 and connected polish rod 160 reciprocate within the liftcylinder 150 between two heads. A first or upper head 152 is placed at adistal end of the cylinder 150, while a second or lower head 154 is at aproximal end of the cylinder 150. The second head 154 has an internalbore that slidably receives the lift cylinder rod 155 duringreciprocation.

The hydraulic oil well pumping system 100 also includes a pair of fluidlines 170, 175. A first fluid line 170 is an oil line. The oil line 170is in fluid communication with the annular area 167 of the lift cylinder150 just above the second (or lower) head 144. The oil line 170 injectsand receives oil from the annular area 167 in order to move the piston155 up and down within the lift cylinder 150. In this way, an up strokeand a downstroke are created for the piston 165 and mechanicallyconnected rod string 130 and downhole pump.

In one aspect, the second fluid line 175 is essentially a vent line. Thevent line 175 receives air and any leaked oil from the piston 165 duringthe upstroke. The vent line 175 is supported by one or more brackets 156disposed along the outer wall of the lift cylinder 150. In anotherarrangement, the second fluid line 175 is a pressure line that allowsoil to push the piston 165 down on the downstroke. Operation of athree-way proportional valve that directs the flow of oil through lines170 and 175 in this embodiment is discussed further, below.

Related components of the hydraulic oil well pumping system 100 areshown schematically. These include a prime mover 182, a hydraulic pump184, control valves 190, and a fluid reservoir 195. These components areoptionally supported together on a movable skid 180.

The prime mover 182 provides power to the pump 184. The prime mover 182may be a gasoline engine, a diesel engine, or other internal combustionengine. Alternatively, the prime mover 182 may be an electric motor.When the prime mover 182 is started, it activates the hydraulic pump184. Beneficially, changing the operating speed of the prime mover 182will vary the output of the pump 184. Further, control logic may be usedin connection with a timer to cyclically turn the pump 184 on and off orto open and close control valves 190 as is known in the art. Thus,control valves 190 will include electrical circuitry.

The pump 184 serves to pump fluid into the oil line 170. The pump 184 ispreferably a piston style pump. However, other types of pumps such as avane-type pump may be employed. The pump 184 may be a fixed displacementpump or a variable displacement pump. A hydraulically driven air fan(not shown) may be used to force air across hydraulic and compressorcoolers. This helps to keep components from overheating.

When the pump 184 is stopped, or when the valves 190 redirect flow awayfrom the oil line 170, the valves 190 permit oil to return to the fluidreservoir chamber 195. This may be done, for example, through arestricted orifice. Oil returns to the fluid reservoir chamber 195through the restricted orifice (or other valve) in response togravitational forces applied to the piston 165 by means of the harnesssystem 140 and connected rod string 130 and downhole pump.

The lift cylinder 150 and harness system 140 reside over a wellhead 105.The wellhead 105 serves to support a string of casing 108 that extendsfrom the surface 101 and down into a wellbore 115. In addition, thewellhead 105 supports a string of production tubing 120 within thecasing 108.

It is understood that FIG. 1 only shows the wellhead 105 and an upperportion of the wellbore 115, and that the wellbore 115 will actuallyextend many hundreds and, likely, many thousands of feet down into theearth surface 110. Further, it is understood that the wellbore 115 willemploy not just one string of casing (such as casing string 108), butalso several strings of casing (not shown) extending down to a producingformation having one or more zones of interest. Additionally, theproduction tubing 120 will extend down to at least a top zone ofinterest. Finally, it is understood that many wellheads reside over aso-called cellar (not shown) at the surface 101.

The wellhead 105 includes a set of control valves. One such valve isshown at 104, and may be referred to as a master valve. The valves arepart of a “Christmas tree,” shown via bracket 102. The valves of theChristmas tree 102 direct the flow of production fluids and also permitan operator to inject treatment chemicals or to otherwise access theproduction tubing 120. The Christmas tree 102 controls formationpressure both within and on the back side of the production tubing 120.An annular area 125 is shown for the back side of the production tubing120.

Residing below the Christmas tree 102 and within the wellbore 115 is arod string 130. The rod string 130 is comprised of a plurality of long,slender joints of steel, known as sucker rods. Each sucker rod istypically 25 or 30 feet in length. The rod string 130 supports a pump(not shown) downhole. The pump, in turn, moves production fluids fromthe subsurface formation, up the production tubing 120, and to thewellhead 105 through positive displacement. The pump is generallypositioned next to a perforated zone of the wellbore 115. The productionfluids then flow from a valve in the Christmas tree 102, such as valve104, where they may undergo some initial fluid separation and are thendirected into a flow line or a gathering tank (not shown). (Note that aproduction line is not shown in FIG. 1, but those of ordinary skill inthe art will well understand that reservoir fluid lines extend from awell site.

Each sucker rod includes a coupling. In FIG. 1, a coupling 134 is shownabove the rod string 130. In this view, the coupling 134 connects therod string 130 to a polish rod 160. The polish rod 160, in turn, extendsup through the wellhead 105, and through the Christmas tree 102.Suitable packing 106 is provided to prevent production fluids fromleaking out of the Christmas tree 102.

FIG. 2 is an enlarged side view of a portion of the hydraulic oil wellpumping system 100 of FIG. 1. Here, the lift cylinder 150, the liftcylinder rod 155, the polish rod 160, the harness system 140 and the twocompressor cylinders 145 are more clearly seen. In addition, a frame ora tripod is shown that is used to stabilize the lift cylinder 150 overthe wellbore 115. This optional feature is most commonly used in windylocations. In the view of FIG. 2, the tripod includes an upperhorizontal bar 141, a lower horizontal bar 147, and vertical bars 149.In the arrangement of FIG. 2, only two vertical bars 149 are shown.However, it is understood that a third vertical bar 149 is used, andresides behind the polish rod 160 and the lift cylinder rod 155.

The polish rod 160 defines an elongated cylindrical body. An upperportion of the polish rod 160 extends through a block 146 that is partof the harness system 140. A set of rod clamps 143 holds the polish rod160 to the block 146. In this way, the polish rod 160 is mechanicallyconnected to the harness system 140.

The harness system 140 includes a wheel, or pulley 148. A bridle cable147 is wound around the pulley 148 and connects to the block 146. Thepulley 148 and bridle cable 147, in turn, are connected to an uppersupport bar 144 of the harness system 140.

The upper support bar 144 includes several pins. First, pin 149′pivotally connects the upper support bar 144 to the lift cylinder rod155. Then, opposing pins 149″ pivotally connect the upper support bar144 to the opposing compressor cylinder rods 142. In this way, as theupper support bar 144 reciprocates, the lift cylinder rod 155 and thecompressor cylinder rods 142 also reciprocate.

FIG. 3 is a side cross-sectional view of a compressor system 300 of thepresent invention, in one embodiment. The system includes one of thecompressor cylinders 145 of FIG. 1, in one embodiment, indicated at 345.The compressor cylinder 345 may be, for example, a six-inch i.d. barrel.The compressor cylinder 345 includes an upper end 312 and a lower end314. The upper end 312 includes an outlet 316 that is in fluidcommunication with a fluid reservoir (shown schematically at 318), whilethe lower end 314 is closed.

A bore 305 is formed within the cylinder 345. The bore 305 houses acompressor cylinder rod 342. Compressor cylinder rod 342 corresponds torods 142 of FIGS. 1 and 2. In the view of FIG. 3, the compressorcylinder rod 342 is in mid-stroke.

An annular area 315 is formed between the cylinder rod 342 and thesurrounding cylinder 345. The annular area 315 is sealed at the bottomof the rod 342 using a suitable packer or seal. A piston 346 is seensealing the annular area 315. The piston 346 is at least partiallysecured in place by a nut 361 that is threadedly connected to a threadedend 341 of the compressor cylinder rod 342. A spacer 363 is optionallyplaced between the piston 346 and the nut 361 to fill a void that may beleft between the piston 346 and the nut 361.

Above the piston 346, the bore 305 is at least partially filled withoil. The oil is used for cooling and lubricating the cylinder 345. Asthe piston 346 moves on its upstroke, the lubricating oil moves throughthe outlet 316 and into the reservoir 318.

In one aspect, the fluid reservoir 318 is shared with the reservoir 195for the hydraulic oil well pumping system 100. Check valves (not shown)are provided so that when the oil is pushed from the lift cylinder 155(through oil line 170 during a down stroke), oil is drawn into thecompressor cylinder 345 above the piston 346. During this movement, theoil is preferably passed through a suction filter (not shown). Then,when oil is pushed back into the lift cylinder (through oil line 170during an upstroke), the oil is withdrawn from bore 305 above thecompressor piston 346. However, it is preferred that reservoir 318 beseparate from oil reservoir 195, and that different types of oils beused.

In one trip or the other, the working oil may be routed through an oilcooler. In this way the oil will not only keep the seals and pistons inthe cylinders 150, 345 lubed, but will also take the heat fromcompressing the gas and dissipate it into the air through heat transferprovided by the cooler.

Below the piston 346, the bore 305 is in fluid communication with a pairof pipes 304, 330. Pipe 304 transmits non-condensable hydrocarbonfluids, or produced gas, from the wellbore (seen in FIG. 1 at 115) tothe bore 305 below the piston 346. This takes place during an upstrokeof the compressor cylinder rod 342 and piston 346. During this process,the produced gas (indicated at arrow “G”), is drawn through a one-waycheck valve 340 i and into the bore 305 of the compressor cylinder 345.Then, on the down stroke, the produced gas is moved through one-waycheck valve 340 o and into a dedicated gas line 330.

An upper end of the compressor cylinder rod 342 has a through-opening349 The through-opening 349 is dimensioned to receive pin 149″. In thisway, the rod 342 is pivotally connected to the upper support bar 144 ofthe harness system 140. This, in turn, allows compressor cylinder rod342 to reciprocate with lift cylinder rod 155 and polish rod 160.

Preferably, pressure is monitored in the compressor cylinders 345 (or145) above the compressor pistons 346 (or 146). Hoses (not shown) may beconnected to top portions of the cylinders 345 to make sure thatpressure is equal in the bores 305 of both cylinders 350. This keeps theupper support bar 144 from becoming unlevel. In addition, the bottomside of the respective pistons 346 is configured in such a way that whenthe compressor cylinder rods 342 are retracted, the bore 305 isevacuated in order to pull in as much gas as possible. This increasesthe efficiency of the gas compression. Preferably, the pistons 346comprise durable elastomeric rings.

FIG. 4A is schematic view of a hydraulic pumping system 400 of thepresent invention, in one arrangement. The system 400 resides overwellbore 415, which corresponds to wellbore 115 of FIG. 1. Here, a liftcylinder piston 450 and an operatively connected compressor cylinderpiston 442 are on their down strokes. Arrows “D” indicate the directionof the pistons 450, 442.

The hydraulic pumping system 400 includes a pump 184. The pump 184 ispreferably a hydraulic pump, such as a fixed or variable displacementhydraulic pump. The hydraulic discharge of the pump 184 is controlled bya control valve. The control valve may be directed through aprogrammable logic controller. The control valve directs the movement ofa lift piston 465 within the lift cylinder 450. Preferably, anapproximately 87-inch stroke is provided.

The pump 184 is designed to pump a working fluid such as a clean orrefined oil from the reservoir 195 through an oil line 170. This takesplace during the upstroke, shown separately in FIG. 4B. En route to thelift cylinder 450, the oil may travel through a directional controlvalve (not shown). The control valve may be, for example, a proportionalvalve or it may be part of a variable speed prime mover. In anyembodiment, the control valve allows hydraulic oil to be pumped from thepump 184 to an annular area (such as area 167 of FIG. 1) through oilline 170.

The hydraulic pumping system 400 also includes a return line 175 and areservoir 195. A downstroke control valve (not shown) may be provided topermit oil to return to the fluid reservoir 195 via a restrictedorifice. This takes place when the directional control valve is in its“neutral” position. Since pressure no longer forces the piston 465upward, it begins to drop in response to gravitational forces applied tothe piston 460 by means of the rod string 460 and connected downholepump. This takes place during the downstroke presented in FIG. 4A.

In one aspect, the return line 175 serves as a pressure line. In thisinstance, line 175 is an upper oil line. Pressure may be provided to theupper oil line 175 during the downstroke as a means of controllingstroke length, cycle time, or both. Pressure may also be applied in line175 at the end of the upstroke to prevent (or at least minimize) bumpingor jarring of the piston 165 at the peak of the upstroke.

In one aspect, the main hydraulic directional control valve is athree-position proportional valve having load sense ports. The positionsdefine an upstroke position, a downstroke position, and neutral. In theneutral position, ports placed in the lift cylinder 150 for the loweroil line 170 and the upper oil line 175 are blocked. The pump 184 willgo into standby mode when it is not moving any oil. Both of the cylinderports are blocked, holding the piston 165 in position.

The directional control valve will be part of the control valves shownat 190. The control valves 190 will operate with coils. As a first coilis energized, it sends a signal to open a port associated with oil line170. This sends pressured oil to the bottom side of the lift piston 165,and simultaneously drains oil from the top side of the lift piston 165.Oil is sent to the reservoir 195, allowing the piston 165 to move in anupstroke. Then, the proportional control valve receives a new signal,such as a pulse-width modulation (“PWM” signal) from a processor (orprogrammable logic controller, or “PLC”) to discontinue the flow of oilinto oil line 170. This preferably takes place in response to feedbackfrom a position sensor strategically located along the lift cylinder 150at the top of the piston stroke.

It is observed that the PWM signals may start out weak, and thenincrease to a desired level to provide smooth starts and stops. Thesignals control the maximum opening amount of valves and the open times.This cycling of signals also serves to control speed and stroke length.In this embodiment, separate upstroke and downstroke control valves arenot required.

To begin the downstroke, a separate coil associated with theproportional control valve may be energized. This causes pressured oilto enter the lift cylinder 150 from the upper oil line 175 above thelift piston 165. At the same time, the port associated with the lowerline receives a back flow of oil from below the piston 165. This processis again controlled by PWM signals from the PLC, with smooth startingand stopping. In one aspect, the PLC is a Maple Systems controllerhaving a color touch screen.

It is noted here that many hydraulic drive/control units for hydraulicrod pumping systems are known. One such system is described in U.S.Patent Publ. No. 2009/0194291, filed by Petro Hydraulic Lift Systems,LLC of Jennings, La. (now part of Lufkin Industries, Inc. of Houston,Tex.) Aspects of such as system are suitable for use in the system 100herein. The 2009/0194291 is incorporated herein in its entirety byreference.

In FIG. 4A, compressor cylinder piston 446 is moving down with thecompressor cylinder rod 442. This simultaneously causes produced gas tomove to a downstream facility 435 through line 430. The downstreamfacility 435 may be a gas separator or a treating unit (such as acryogenic separator or an amine chemical separator). Alternatively, thedownstream facility 435 may be a gathering facility for downstreamtransmission. Alternatively still, the downstream facility 435 may be adrill site where gas is gathered for use as a combustible fuel indriving engines on a drilling rig. Still further, where the gas isalmost completely a clean burning fuel such as methane, the downstreamfacility 435 may simply be a tank used directly for fuel.

In one aspect, the wellbore 415 is about 6,500 feet in true-verticaldepth. The weight of the rod string and connected downhole pump areabout 9,000 pounds. In this instance, the force required to compress thegas in line 430 in both cylinders will be around 11,000 pounds at 225psi line pressure. Therefore, the rod string 430 falling back down (asshown in FIG. 4A) will supply 9,000 pounds of force, while hydraulicswill provide the additional 2,000 pounds as needed. If the well psistays around 50 psi, then the compressor cylinders 445 will need toprovide about 3,000 pounds of lift on the upstroke (as shown in FIG.4B), reducing power requirements for the hydraulic system, therebycreating greater working efficiency.

It is noted that certain steps may be taken to increase efficiency ofthe hydraulic pumping system 400. These may include increasing the innerdiameter of the compressor cylinders 445, thereby allowing more gas toflow into the line 430. These may also include turning the pump on andoff as gas psi increases and decreases or as fluid volume increases ordecreases from the wellbore 415.

FIG. 4B provides another schematic view of the hydraulic pumping system400 of FIG. 4A. Here, the lift cylinder piston 465 and operativelyconnected compressor cylinder piston 442 are on their up strokes. InFIG. 4B, compressor cylinder piston 446 is moving up with the compressorcylinder rod 442. This causes produced gas from the wellbore 415 to bedrawn into the compressor cylinder 445 below the piston 446. At the sametime, oil is brought to the surface 401 and moved downstream throughseparate surface pipe 406.

It is noted that it is desirable for the operator to know where thepiston 465 is within the cylinder 450 during any given part of thecycle. One reason is so that speed control may be applied to the pump184. Specifically, the operator may wish to decrease the speed of thepump 184, and thus decelerate the piston 465 and rod string at the endsof the upstrokes and down strokes. This prevents bumping and jarring asdiscussed above.

Hydraulically actuated reciprocating sucker rod pump systems havehistorically employed sensors along or above the wellhead. The sensorsmay be mechanical, hydro-mechanical, pneumatic, pneumatic-mechanical,acoustic, electronic or electro-mechanical position indicating devicesused to detect the position of a piston. For example, U.S. Pat. No.7,762,321 teaches the use of a plurality of “proximity switches” alongthe actuation cylinder to detect the location of an object along thepiston. When a proximity switch detects the object, a limit switch isactivated that de-energizes a valve. Sensors have also been used todetect travel speed or direction and are used to send signals to aprocess that may control piston position, speed or direction. The system400 is compatible with the use of such sensors and control systems.

FIG. 4C demonstrates one possible use of a sensor for the hydraulic rodpumping system 100. A sensor 455 is shown proximate an upper end of thehydraulic cylinder rod 155. The sensor 455 interacts with a magnet 450to provide location, or position, of the piston 165.

In the view of FIG. 4C, the hydraulic cylinder 150 is seen in anenlarged view. The hydraulic cylinder 150 defines a tubular wall 413that houses the elongated lift cylinder rod 155. The lift cylinder rod155 moves between upper and lower rod positions in response to hydraulicpressure applied to the piston 165. The lift cylinder rod 155 is affixedto the lift piston 165, and travels with it. In the arrangement of FIG.4C, the lift cylinder rod 155 actually extends through a cap 436 andabove the hydraulic cylinder 150.

Also visible in FIG. 4C is an enlarged upper portion of the frame thatis used to stabilize the lift cylinder 150 over the wellbore. The frameagain includes an upper horizontal bar 141, a lower horizontal bar (notshown in FIG. 4C), and three (or more) vertical bars 149. The frame 149forms an interface between the cylinder wall 413 and the wellhead (seenat 105 in FIG. 1).

At the lower end portion of the lift cylinder rod 155 is provided theharness 140. Only an upper portion of the harness 140 is shown in FIG.4C. It is understood that the harness supports the polish rod, shown at160 in FIG. 1, and seen partially at the bottom of FIG. 4C.

The hydraulic cylinder 150 includes an upper port 475 and a lower port470. The upper port 435 can be a part of cap 436 which is fastened to anupper end portion of the cylinder body 213. FIG. 4C illustrates acondition wherein the piston 165 is at the peak of its upstroke, asindicated by arrows 441. Lower port 470 is receiving inflow of hydraulicfluid as indicated by the arrows 440. Fluid above piston 165 isevacuated via upper port 475. Arrows 442 indicate schematically the flowdirection of oil as the piston 165, lift cylinder rod 155, and polishrod 160 are elevated. The harness system 140 (shown in FIG. 1) will alsobe elevated.

The magnet 450 is mounted on top of a cap 436. Upper port 475 extendsinto the cap 436. The magnet 450 communicates with the position sensor455. The position sensor 455 is illustratively used in lieu of proximitysensors or switches. Preferably, the sensor 455 actually resides withina hollow lift cylinder rod 155. The sensor's proximity to the magnet 450determines the location of the piston 165 at all times.

Using the hydraulic rod pumping system 100 described above, a method forcompressing produced gas at a well site is also provided herein. FIGS.5A-5B provide a flow chart showing steps that may be performed for sucha method 500, in one embodiment. In the method, the well site has awellbore that extends into an earth surface. The method 500 employs apumping system as described above, including a pump with an oil linethat cyclically directs hydraulic fluid into a lift cylinder over awellhead. The pressure created by the hydraulic fluid causes a pistonand operatively connected rod string and downhole pump to reciprocate.This, in turn, causes reservoir fluids to be produced from the wellboreto the surface through positive displacement.

Referring now to FIG. 5A, the method 500 first comprises providing anelongated hydraulic lift cylinder. This is shown at Box 510. The liftcylinder is positioned over the wellbore such as in the arrangementshown in FIGS. 1 and 4A.

The method 500 also includes providing a lift piston. This step isprovided at Box 515. The lift piston may be in accordance with thepiston 165 of FIG. 1. The lift piston is movable between upper and lowerrod positions within the lift cylinder. The lift piston creates anannular seal below the piston between a connected lift cylinder rod andthe surrounding lift cylinder. Hydraulic pressure acts against the liftpiston to cause the lift piston to move.

The method 500 further includes operatively connecting the lift pistonto a rod string. This is done through a harness system (such as system140 of FIG. 1) that mechanically connects the lift cylinder rod with apolish rod and connected rod string. This is shown at Box 520. When thelift piston reciprocates, the polish rod and connected rod stringreciprocate with it. Preferably, the rod string moves within a string ofproduction tubing that extends down to the depth of a subsurfacereservoir.

The rod string extends downwardly from the polish rod and into thewellbore. The rod string has a downhole pump connected to it for liftingfluids to the surface in response to reciprocation of the rod string.

The method 500 also includes providing a hydraulic pump. This is seen atBox 525. Preferably, the pump is a variable displacement pump. The pumpis powered by a prime mover. The prime mover may be an electric motor,an internal combustion engine, or other driver.

The method 500 also has the step of connecting the pump and thehydraulic cylinder with an oil line. This is indicated at Box 530. Theoil line transmits hydraulic fluid from the pump to the lift cylinder.

Optionally, the method 500 includes providing a directional controlvalve. This is given at Box 535. The directional control valve movesbetween upstroke and downstroke flow positions in response to signalsfrom an electrical control system. When the valve is in its openposition, it directs hydraulic fluid such as oil from the pump, throughthe oil line and into an annular area formed between the piston and thesurrounding lift cylinder. In the neutral position, the control valveallows oil to flow back from the lift cylinder to the reservoir througha downstroke control valve.

The method 500 also has the step of providing a fluid reservoir. This isshown at Box 540. The reservoir contains hydraulic fluid to be suppliedto the pump. During operation, the hydraulic fluid level will rise andfall in the reservoir chamber on each stroke of the lift piston.

The method 500 next includes providing a reservoir line. This is seen atBox 545. The reservoir line transmits hydraulic fluid from the liftcylinder back to the reservoir. Optionally, a filter is provided alongthe reservoir line.

The method 500 optionally also has the step of providing a down strokecontrol valve (not shown). The downstroke control valve may have variouspassages allowing unrestricted flow in one direction (the upstrokedirection), and restricted flow in the other direction (the downstrokedirection). The down stroke control valve chokes the flow of fluid fromthe cylinder back to the reservoir. This, in turn, limits the rate offlow of hydraulic fluid. The downstroke control valve may be a discretevalve. Alternatively, he downstroke control valve may be a nitrogenaccumulator or any other device that captures the energy from thegravitational fall of the piston and connected polish rod, rod stringand downhole pump.

Also, the method 500 includes providing at least one compressorcylinder. This is indicated at Box 550. Each compressor cylinder has acompressor piston that is movable between upper and lower rod pistons inresponse to movement of the lift piston. Thus, the compressor pistonsare operatively connected to the lift pistons so that when hydraulicpressure reciprocates the lift piston and operatively connected rodstring, the at least one compressor cylinder is also reciprocated.

In addition, the method 500 includes placing the at least one compressorcylinder in fluid communication with a gas line. This is provided at Box555. The line resides at the surface and is used to transportnon-condensable hydrocarbon fluids such as methane and ethane.Additional components of the non-condensable hydrocarbon fluids mayinclude hydrogen sulfide, carbon dioxide, propane, and argon. Thenon-condensable hydrocarbon fluids are permitted to invade thecompressor cylinders below the respective compressor pistons duringupstrokes of the compressor cylinder rods.

Further, the method 500 has the step of producing non-condensablehydrocarbon fluids from the wellbore and into the gas line. This isshown at Box 560. Production is preferably done by allowing gases tomigrate from a subsurface reservoir and up the wellbore behind thestring of production tubing. The gases are directed into the gas line bythe wellhead.

The method 500 additionally provides for reciprocating the at least onecompressor piston in order to increase pressure in the gas line. This isseen at Box 565. When the compressor piston moves on its upstroke, itdraws gas in from the wellbore and into the bore of the compressorcylinder. Then, when the compressor piston moves down on its downstroke,it compresses the gas and moves the gas along the gas line downstream.

Also, the method 500 includes reciprocating the lift piston andmechanically connected rod string within the wellbore. This is indicatedat Box 570. The step of Box 570 is the natural result of operation ofthe hydraulic pumping system in order to pump oil from the wellbore.

It is observed that during the design of the hydraulic oil well pumpingsystem 100, a stroke length must be determined for the lift piston andconnected lift cylinder rod. The stroke length will impact the designedlength for the lift cylinder. Of course, the stroke length will alsoaffect the rate in which fluids are produced to the surface by theconnected submersible pump.

In addition, the stroke length of the lift piston will impact thedesigned length for the compressor cylinders and the housed compressorcylinder rods. Those of ordinary skill in the art will, based on thisdisclosure, understand that the dimensions of the lift cylinder rod andthe compressor cylinder rod need not be identical; however, the liftcylinder (150 in FIG. 1) and the compressor cylinder (145) preferablyneed to be able to accommodate the same stroke length for the liftpiston (165) and the compressor pistons (146).

Additionally still, ring the design of the hydraulic oil well pumpingsystem 100, a determination may be made concerning volume of thecompressor cylinder below the compressor piston. A larger bore volumepermits a greater volume of gases to be received and handled at thesurface. It will be understood though that a greater volume of gases mayrequire greater horsepower, or force, from the lift piston during thedownstroke. Hence, the proportional valve embodiment described above maybe of benefit in helping the rod string “push” the compressor pistondown against the non-condensable fluids and through the gas line.

As can be seen, a method for compressing gas while pumping oil, usedspecifically for actuating a sucker rod string and bottom hole plungerpump in oil or gas wells, is offered herein. It is understood that thehydraulic oil well pumping system 100 of FIG. 1 and the method 500 forcompressing gas of FIG. 5 are merely illustrative. Other arrangementsmay be employed in accordance with the claims set forth below. Further,variations of the method for determining position of the piston may fallwithin the spirit of the claims, below.

For example, while embodiments described herein have provided for theoil line 175 actuating the lift piston 165 and mechanically connectedpolish rod 160 and rod string 130, and the harness system 140 therebymoving the compressor cylinder rods 142 in response, that the inversecould also be applied. In this respect, the oil line 175 may act againstrespective lift pistons (not shown) in upper ends of the compressorcylinders 145, causing direct reciprocation of the compressor cylinderrods 142 and, thereby, consequential reciprocation of the list piston165 through the harness system 140. It will be appreciated that theinventions are susceptible to other such modifications, variations andchanges without departing from the spirit thereof.

I claim:
 1. A hydraulic oil well pumping system, comprising: anelongated hydraulic lift cylinder; a lift piston that is movable betweenupper and lower rod positions within the lift cylinder; a rod stringthat is operatively connected to the lift piston, the rod string beingconfigured to extend into a wellbore; a downhole pump positioned in thewellbore proximate a lower end of the rod string for pumping reservoirfluids up the wellbore; at least one compressor cylinder; and acompressor piston residing within each of the at least one compressorcylinder, the compressor piston being configured to reciprocate withinthe compressor cylinder in response to movement of the lift piston andthe operatively connected rod string; wherein the at least onecompressor cylinder is in fluid communication with a gas line thatreceives non-condensable fluids produced from a wellbore below thecompressor piston such that pressure is added to the gas line when thecompressor piston moves on a down stroke.
 2. The hydraulic oil wellpumping system of claim 1, further comprising: a hydraulic pumpconfigured to cyclically pump a work fluid into a bore of the liftcylinder to act on the lift piston.
 3. The hydraulic oil well pumpingsystem of claim 1, further comprising: a prime mover; a hydraulic pumpthat is powered by the prime mover; a control valve that moves betweenupstroke and down stroke flow positions; an oil line connecting the pumpand the hydraulic cylinder, the control valve being positioned in theoil line so that it can direct flow between the hydraulic pump and thelift cylinder; a fluid reservoir for containing hydraulic fluid to besupplied to the pump.
 4. The hydraulic oil well pumping system of claim3, further comprising: a reservoir line that transmits hydraulic fluidfrom the cylinder to the reservoir; and wherein the hydraulic fluid is arefined oil.
 5. The hydraulic oil well pumping system of claim 3,wherein: the prime mover is an electric motor or an internal combustionengine; and the rod string is mechanically connected to the pistonthrough a polish rod.
 6. The hydraulic oil well pumping system of claim1, wherein the non-condensable fluids comprise methane, ethane, orcombinations thereof.
 7. The hydraulic oil well pumping system of claim1, wherein the gas line is in fluid communication with (i) a gastreating unit in an oil field, (ii) a gas gathering facility, or (iii) astorage tank in an oil field.
 8. The hydraulic oil well pumping systemof claim 1, wherein: the non-condensable fluids comprise primarilymethane, ethane, or combinations thereof; and the gas line is in fluidcommunication with a storage tank at a drill site.
 9. The hydraulic oilwell pumping system of claim 1, wherein the lift piston is operativelyconnected to the rod string by means of: a lift cylinder rod connectedto the lift piston and that extends below the lift cylinder; a polishrod that extends through a well head and into the wellbore, and iscoupled to the rod string; and a harness system connected to a lower endof the lift cylinder rod, and also connected to an upper end of thepolish rod, the harness system having a block for receiving an upper endof the polish rod and a clamp for securing the polish rod over theblock.
 10. The hydraulic oil well pumping system of claim 8, furthercomprising: a compressor cylinder rod residing with each of the at leastone compressor cylinder, with each of the compressor cylinder rods beingoperatively connected to a respective compressor cylinder pistonproximate a lower end, and to the harness system at an opposing upperend such that the compressor cylinder piston and connected compressorcylinder rods reciprocate with the lift piston and connected liftcylinder rod.
 11. A method of compressing produced gas at a well site,the well site having a wellbore that extends into an earth surface, andthe method comprising: providing an elongated hydraulic lift cylinder,the lift cylinder having a lift piston that is movable between upper andlower rod positions within the lift cylinder; operatively connecting thelift piston to a rod string, wherein the rod string extends downwardlyfrom the lift piston and into the wellbore; providing a downhole pump inthe oil well proximate a lower end of the rod string; providing ahydraulic pump that is powered by a prime mover; fluidically connectingthe hydraulic pump and the hydraulic cylinder with an oil line thatcyclically transmits hydraulic fluid from the pump into the liftcylinder to act against the lift piston; providing at least onecompressor cylinder, each of the at least one compressor cylinder havinga compressor piston that is movable between upper and lower rodpositions with reciprocating movement of the lift piston; placing the atleast one compressor cylinder in fluid communication with a gas line;producing non-condensable hydrocarbon fluids from the wellbore and intothe gas line; reciprocating the lift piston and operatively connectedrod string and downhole pump in order to pump condensable hydrocarbonfluids from the wellbore to a surface; and reciprocating the compressorpiston with the lift piston in order to increase pressure in the gasline and move the non-condensable hydrocarbon fluids through the gasline.
 12. The method of claim 11, further comprising: providing adirectional control valve that moves between upstroke and downstrokeflow positions such that when the valve is in its upstroke position, itdirects the hydraulic fluid from the pump and into an annular areaformed below the lift piston between a lift cylinder rod and thesurrounding lift cylinder, and when the directional control valve is inits downstroke position, it receives reverse flow from the liftcylinder; and providing a fluid reservoir for containing hydraulic fluidto be supplied to the pump.
 13. The method of claim 12, wherein: themethod further comprises providing a reservoir line that transmitshydraulic fluid from the cylinder to the reservoir; and the hydraulicfluid is a refined oil or an aqueous fluid.
 14. The method of claim 13,wherein: the prime mover is an electric motor or an internal combustionengine; and the rod string is mechanically connected to the pistonthrough a polish rod.
 15. The method of claim 11, wherein thenon-condensable hydrocarbon fluids comprise methane, ethane, orcombinations thereof.
 16. The method of claim 15, further comprising:transporting the non-condensable hydrocarbon fluids through the gas lineto (i) a gas treating unit in an oil field, (ii) a gas transmissionline, (iii) a storage tank in an oil field, or (iv) a storage tank at adrill site.
 17. The method of claim 11, wherein: the lift piston isconnected to a lift cylinder rod within the lift cylinder, the liftcylinder rod extending below the lift cylinder; and a polish rod extendsthrough a well head and into the wellbore, and is coupled to the rodstring.
 18. The method of claim 17, wherein operatively connecting thelift piston to the rod string comprises connecting a lower end of thelift cylinder rod to a harness system, and connecting an upper end ofthe polish rod to the harness system, the harness system having a blockfor receiving an upper end of the polish rod and a clamp for securingthe polish rod over the block.
 19. The method of claim 18, wherein thelift cylinder rod and the polish rod are the same rod.
 20. The method ofclaim 18, wherein: each of the compressor cylinders comprises acompressor cylinder rod; and each of the compressor cylinder rods isoperatively connected to a respective compressor cylinder pistonproximate a lower end, and to the harness system at an opposing upperend such that the compressor cylinder piston and connected compressorcylinder rods reciprocate with the lift piston and connected liftcylinder rod.